Aromatic polymer's molecular structure makes it difficult to produce in any format other than thin sheets, but the team found a way to 3D print the material.

Viriginia Tech researchers are 3D printing with new materials previously unusable with this method.

A team of Virginia Tech College of Engineering and College of Science researchers includes (left to right) Viswanath Meenakshisundaram, Charles Carfagna, Christopher Williams, Justin Sirrine, and Timothy Long. (Photo courtesy of Virginia Tech)

The team has created a new way to 3D print polyimide, a type of high-temperature polymeric material that has been commonly used to insulate space craft and satellites from the extreme temperatures of space.

Previously called Kapton, this material is an aromatic polymer composed of carbons and hydrogens inside benzene rings — providing exceptional thermal and chemical stability. However, the molecular structure makes this material difficult to produce in any format other than thin sheets.

For the past year, researchers at the College of Engineering and College of Science were able to synthesize the macromolecules, making them stable enough to maintain their thermal properties during the 3D printing process.

“Conventional processing routes have limited engineers to make only thin films from these materials,” said Christopher Williams, an associate professor with the Department of Mechanical Engineering in the College of Engineering and leader of the Design, Research, and Education for Additive Manufacturing Systems (DREAMS) Laboratory. Williams explains that they are now able to 3D print with these materials, which will allow the team to start designing objects with complex shapes and take advantage of the technology.

This raw 3D printed ploymeric material known as Kapton, might one day be used in space vehicles or satellites because of its ability to withstand high temperatures. (Photo courtesy of Virginia Tech)

One of the benefits of this new method is that the material can maintain its properties. Typically, printable polymers start to lose their mechanical strength at about 300°F. The findings suggest that this polymer can maintain properties above above 680°F.

“We are now able to print the highest temperature polymer ever – about 285°F higher in deflection temperature than any other existing printable polymer,” Williams explains. The 3D printed material has comparable strength to the conventionally processed thin-film Kapton material.

An early breakthrough was identified at the lab of Timothy Long, a professor with the Department of Chemistry, part of the College of Science, and also the director of the Macromolecules Innovation Institute (MII), located within Virginia Tech’s Institute for Critical Technology and Applied Science. Williams is associate director of MII. Long, with then-post-doctorate researcher Maruti Hegde, now a research associate at the University of North Carolina at Chapel Hill, was exploring the possibility of making 3D printed shapes from aromatic polymers, such as Kapton. They discovered that they were able to derive the novel polymer synthesis design, allowing the polyimide to be 3D printed.

Williams’ lab, led by College of Engineering doctoral students Viswanath Meenakshisundaram, of Bangalore, India, and Nicholas Chartrain, of Westfield, New Jersey, then exacted the process for 3-D printing.

“We chose a fairly ubiquitous high-temperature and high-strength polymer because we wanted to enable a rapid impact on existing technologies,” explains Timothy Long, a professor with the Department of Chemistry, part of the College of Science, and also the director of the Macromolecules Innovation Institute (MII). Long adds companies have already shown early interest in the new material, which has a U.S. patent filed.

The two teams spent a year testing the new material’s performance and fine-tuning how the material is printed.

Williams’ and Long’s work recently was published in the Advanced Materials Journal.